Guaranteeing the event order for multi-stage processing in distributed systems

ABSTRACT

Systems and methods for guaranteeing the event order for multi-stage processing in distributed systems are disclosed. In some examples, a warm-up period is used to accurately determine a starting point for ordered events of an event stream. Skip-beats may be utilized as dummy events so that the event processor does not wait too long for events that were filtered out at earlier stages.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a non-provisional application of, and claims the benefit and priority under 35 U.S.C. 119(e) of U.S. Provisional Application No. 62/244,452, filed Oct. 21, 2015, entitled “GUARANTEEING THE EVENT ORDER FOR MULTI-STAGE PROCESSING IN DISTRIBUTED SYSTEMS,” the entire contents of which is incorporated herein by reference for all purposes.

BACKGROUND

In traditional database systems, data is stored in one or more databases usually in the form of tables. The stored data is then queried and manipulated using a data management language such as a structured query language (SQL). For example, a SQL query may be defined and executed to identify relevant data from the data stored in the database. A SQL query is thus executed on a finite set of data stored in the database. Further, when a SQL query is executed, it is executed once on the finite data set and produces a finite static result. Databases are thus best equipped to run queries over finite stored data sets.

A number of modern applications and systems however generate data in the form of continuous data or event streams instead of a finite data set. Examples of such applications include but are not limited to sensor data applications, financial tickers, network performance measuring tools (e.g. network monitoring and traffic management applications), clickstream analysis tools, automobile traffic monitoring, and the like. Such applications have given rise to a need for a new breed of applications that can process the data streams. For example, a temperature sensor may be configured to send out temperature readings.

Managing and processing data for these types of event stream-based applications involves building data management and querying capabilities with a strong temporal focus. A different kind of querying mechanism is needed that comprises long-running queries over continuous unbounded sets of data. While some vendors now offer product suites geared towards event streams processing, these product offerings still lack the processing flexibility required for handling today's events processing needs.

SUMMARY

The following portion of this disclosure presents a simplified summary of one or more innovations, embodiments, and/or examples found within this disclosure for at least the purpose of providing a basic understanding of the subject matter. This summary does not attempt to provide an extensive overview of any particular embodiment or example. Additionally, this summary is not intended to identify key/critical elements of an embodiment or example or to delineate the scope of the subject matter of this disclosure. Accordingly, one purpose of this summary may be to present some innovations, embodiments, and/or examples found within this disclosure in a simplified form as a prelude to a more detailed description presented later.

A further understanding of the nature of and equivalents to the subject matter of this disclosure (as well as any inherent or express advantages and improvements provided) should be realized in addition to the above section by reference to the remaining portions of this disclosure, any accompanying drawings, and the claims.

In some examples, a method, a system, and a computer-readable medium may be provided. The method, the system, and/or the computer-readable medium may comprise determining a first event of a sequence of events that are received as part of an event stream, initializing a value of an event counter with a timestamp of the first event, and/or processing additional events of the event stream. In some cases, the method, system, and/or computer-readable medium may also comprise identifying a filtered event of the event stream, generating a skip-beat for the filtered event, and/or inserting the skip-beat into the event stream. Further, in some examples, the method, system, and/or computer-readable medium may also comprise receiving subsequent events of the event stream, identifying an out-of-order event of the event stream, and/or processing subsequent events in order of the timestamp associated with each of the subsequent events independent of whether a next event in the event stream is an actual event or a skip-beat. In some instances, the method, system, and/or computer-readable medium may also comprise determining the first event by starting a timer, receiving a set of events of the sequence of events until the timer expires, re-sequencing the set of events in chronological order, and identifying the first event as an event of the re-sequenced set with a highest timestamp. Additional events may be batched before the timer expired. The filtered event may have been filtered out by an upstream stage. The actual event may comprise event data corresponding to the event stream.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to reasonably describe and illustrate those innovations, embodiments, and/or examples found within this disclosure, reference may be made to one or more accompanying drawings. The additional details or examples used to describe the one or more accompanying drawings should not be considered as limitations to the scope of any of the claimed disclosures, any of the presently described embodiments and/or examples, or the presently understood best mode of any innovations presented within this disclosure.

FIG. 1 is a simplified illustration of a system that may incorporate an embodiment of the present disclosure.

FIG. 2 is a simplified block diagram of details for implementing an embodiment of the present disclosure.

FIG. 3 is a flowchart of a method for implementing an embodiment of the present disclosure.

FIG. 4 is a flowchart of a method for implementing an embodiment of the present disclosure.

FIG. 5 is a flowchart of a method for implementing an embodiment of the present disclosure.

FIG. 6 depicts a simplified diagram of a distributed system for implementing some of the examples described herein, according to at least one example.

FIG. 7 is a simplified block diagram of components of a system environment by which services provided by the components of an embodiment system may be offered as cloud services, in accordance with some of the examples described herein, according to at least one example.

FIG. 8 illustrates an exemplary computer system, in which various embodiments of the present disclosure may be implemented in according with some of the examples described herein, according to at least one example.

DETAILED DESCRIPTION

In Complex Event Processing platforms, to achieve correct results, events should be processed in the order of their application timestamp. If event ‘a’ was produced before event ‘b’ by the application, then event ‘a’ should be processed before ‘b’. For example, to identify a device whose current temperature is greater than the previous temperature, the data should be partitioned by device ID and processed in order. In some examples, the difference between current data and previous data is defined by the timestamp of those events. Ensuring an ordered processing of events is relatively easy in systems where data is ingested from a single point. For example, a partition number for the event can be identified, and the event can be placed on a partition-specific queue for processing. But in distributed systems, ordered processing of events is extremely complex, especially when data is ingested from any node in a cluster. In some cases, a few things should happen to ensure ordered processing. (1) First the start counter with the right sequence number or the timestamp should be initialized. (2) Second, it should be detected whether an event has arrived out of order. (3) Third, the events that have been buffered but not yet processed should be re-sequenced. (4) Lastly, it should be determined when to proceed, so as to not wait indefinitely for an older out of sequence event to arrive. This can especially be the case in multi-stage processing, because they could have been filtered out by a previous processing stage in the pipeline. Through techniques of warm-ups and skip beats, this disclosure provides examples for processing events in order, and in some examples, guaranteeing that events are processed in the order they occur, even if the processing entails multiple stages.

In some examples, one feature of the present disclosure is to account for late events at the very beginning and on system startup. This may be called the warm-up phase. In some examples, a clock is started when the system receives the very first event, and events are collected until the clock or timer expires. After the timer expires, events are re-sequenced and the event with the highest timestamp is used to initialize the value of the counter “LAST_SEEN_TIMESTAMP” and the counter “NEXT_EXPECTED_TIMESTAMP” is set to LAST_SEEN_TIMESTAMP+1. Batched events are processed and the warm-up phase is complete. After the warm-up phase, ordering is strictly enforced using the above two counters.

Another feature of the present disclosure is to trigger a Skip-Beat using the same timestamp as a filtered event. In multi-stage processing, it is feasible that an event is filtered out by an up-stream stage. In such cases the processing system (e.g., a complex event processing (CEP) engine) should not wait indefinitely and attempt event ordering because the filtered event would never arrive. To handle such cases, a Skip-Beat with the same timestamp as the filtered application event can be generated, and the system can propagate the same across all downstream stages. The Skip-Beat is then used in place of the real event to guarantee ordering in an application that deploys multi-stage processing. Once the warm-up phase as described above is complete, the incoming events can processed in the correct order (e.g., subsequent events are processed in order of the timestamp associated with each of the subsequent events); thus, guaranteeing ordered processing of subsequent events, using the following logic

If a real Event or a “Skip-Beat” arrives with the same timestamp as “NEXT_EXPECTED_TIMESTAMP”, the LAST_SEEN_TIMESTAMP is assigned the value of NEXT_EXPECTED_TIMESTAMP and NEXT_EXPECTED_TIMESTAMP is incremented.

If a “Skip-Beat” or a “Real-Event” arrives with a timestamp that is higher than NEXT_EXPECTED_TIMESTAMP, the event is added to a buffer and a Timer with pre-configured expiration interval is started and the behavior below is implemented:

-   -   More incoming Events or Skip-Beats with timestamp higher than         NEXT_EXPECTED_TIMESTAMP are buffered as the timer continues to         run     -   When an incoming Event or Skip-Beat arrives with timestamp same         as NEXT_EXPECTED_TIMESTAMP, the timer is turned off, events in         the buffer is re-sequenced and processed. Please note that the         Skip-Beats will continue to be propagated.     -   When an incoming Event or Skip-Beat arrives with timestamp lower         than NEXT_EXPECTED_TIMESTAMP, the event or beat is discarded as         out-of-band. Again increasing the length of the warm-up phase         can reduce the possibility of this scenario.     -   When the timer expires, buffered events are re-sequenced and         processed while continuing to propagate the Skip-Beats.

These techniques allow for proper initialization of the counters and account for events that may be filtered by an upstream stage in the processing pipeline.

In some examples, a query may be tasked with determining whether an event is higher or lower with respect to an earlier event. For example, whether the temperature has increased in the last hour (or some other time period). However, in order to accurately answer this question, the events (e.g., related to temperature) must be processed in the same order in which they were produced. In a single processor system, or a system that ingests data from a single point, this can be relatively easy by merely queueing events as they come in, and processing them in order. However, in a distributed system, events flow through multiple nodes before they arrive at event processors, and they could be out of order.

As described, one solution is to initialize a start counter with an accurate value so that the event processor has an accurate beginning point. Otherwise, when a system boots up (e.g., after a restart or a reboot), it cannot be assumed that the event processors will start with the correct value. As such, when the system starts up, a warm-up period may be used to determine which event is the appropriate starting event. This starting event may then be used to begin the sequencing. Then, once the processing of events begins, the system needs to be able to detect when something is out of sequence. In some cases, once it is determined that the events are out of sequence, the events must be reordered. However, it may not always be possible to guarantee that an out of sequence event will ever arrive. For example, in some cases, events may be filtered out by an earlier node or process in the distributed system.

In some examples, “skip beats” (e.g., dummy events that are propagated through the system) are used to indicate that the event processor does not need to wait for the particular event. For example, the skip beat may indicate that the event may never arrive. In some cases, if an event has been filtered out by an earlier node, a “skip beat” can be inserted into the stream with the appropriate time stamp (e.g., the same time stamp that corresponded to the filtered event). When the downstream processor receives the “skip beat,” it will be treated as the missing event (e.g., the event that the processor is waiting for of the event that appears to be out of order), and the processor will move on with processing the next event when it is detected. In some examples, an event may be filtered out due to a condition that is processed at an earlier node. For example, if the query is only identifying temperature increases that are above a particular threshold (e.g., greater than 70 degrees or the like), all events associated with temperatures below 60 may be filtered out. When the event is filtered out, a “skip beat” may be inserted into the stream in place of the filtered event. When the event processor identifies the “skip beat,” it will stop waiting for that event.

The event processor may not be aware of which events have been filtered out up-stream. So, if it listens for “skip beat” events, it will learn which events it does not need to process in order (or at all in this case). As noted, the “skip beat” event is essentially a dummy event in place of the real event. So, essentially, if the event processor wants to be able to guarantee accurate ordered event processing, the system must employ at least the above-referenced warm-up period and the use of “skip beats.” Additionally, it may be important to be able to detect when events are out of order.

In some examples, mechanisms to guarantee the event order for multi-stage processing in distributed systems may be provided. In general, a continuous data stream (also referred to as an event stream) may include a stream of data or events that may be continuous or unbounded in nature with no explicit end. Logically, an event or data stream may be a sequence of data elements (also referred to as events), each data element having an associated timestamp. A continuous event stream may be logically represented as a bag or set of elements (s, T), where “s” represents the data portion, and “T” is in the time domain. The “s” portion is generally referred to as a tuple or event. An event stream may thus be a sequence of time-stamped tuples or events.

In some aspects, the timestamps associated with events in a stream may equate to a clock time. In other examples, however, the time associated with events in an event stream may be defined by the application domain and may not correspond to clock time but may, for example, be represented by sequence numbers instead. Accordingly, the time information associated with an event in an event stream may be represented by a number, a timestamp, or any other information that represents a notion of time. For a system receiving an input event stream, the events arrive at the system in the order of increasing timestamps. There could be more than one event with the same timestamp.

In some examples, an event in an event stream may represent an occurrence of some worldly event (e.g., when a temperature sensor changed value to a new value, when the price of a stock symbol changed) and the time information associated with the event may indicate when the worldly event represented by the data stream event occurred.

For events received via an event stream, the time information associated with an event may be used to ensure that the events in the event stream arrive in the order of increasing timestamp values. This may enable events received in the event stream to be ordered based upon their associated time information. In order to enable this ordering, timestamps may be associated with events in an event stream in a non-decreasing manner such that a later-generated event has a later timestamp than an earlier-generated event. As another example, if sequence numbers are being used as time information, then the sequence number associated with a later-generated event may be greater than the sequence number associated with an earlier-generated event. In some examples, multiple events may be associated with the same timestamp or sequence number, for example, when the worldly events represented by the data stream events occur at the same time. Events belonging to the same event stream may generally be processed in the order imposed on the events by the associated time information, with earlier events being processed prior to later events.

The time information (e.g., timestamps) associated with an event in an event stream may be set by the source of the stream or alternatively may be set by the system receiving the stream. For example, in certain embodiments, a heartbeat may be maintained on a system receiving an event stream, and the time associated with an event may be based upon a time of arrival of the event at the system as measured by the heartbeat. It is possible for two events in an event stream to have the same time information. It is to be noted that while timestamp ordering requirement is specific to one event stream, events of different streams could be arbitrarily interleaved.

An event stream has an associated schema “S,” the schema comprising time information and a set of one or more named attributes. All events that belong to a particular event stream conform to the schema associated with that particular event stream. Accordingly, for an event stream (s, T), the event stream may have a schema ‘S’ as (<time_stamp>, <attribute(s)>), where <attributes> represents the data portion of the schema and can comprise one or more attributes. For example, the schema for a stock ticker event stream may comprise attributes <stock symbol>, and <stock price>. Each event received via such a stream will have a time stamp and the two attributes. For example, the stock ticker event stream may receive the following events and associated timestamps:

(<timestamp_N>, <NVDA, 4>)

(<timestamp_N+1>, <ORCL, 62>)

(<timestamp_N+2>, <PCAR, 38>)

(<timestamp_N+3>, <SPOT, 53>)

(<timestamp_N+4>, <PDCO, 44>)

(<timestamp_N+5>, <PTEN, 50>)

In the above stream, for stream element (<timestamp_N+1>, <ORCL, 62>), the event is <ORCL, 62> with attributes “stock_symbol” and “stock_value.” The timestamp associated with the stream element is “timestamp_N+1”. A continuous event stream is thus a flow of events, each event having the same series of attributes.

As noted, a stream may be the principle source of data that CQL queries may act on. A stream S may be a bag (also referred to as a “multi-set”) of elements (s, T), where “s” is in the schema of S and “T” is in the time domain. Additionally, stream elements may be tuple-timestamp pairs, which can be represented as a sequence of timestamped tuple insertions. In other words, a stream may be a sequence of timestamped tuples. In some cases, there may be more than one tuple with the same timestamp. And, the tuples of an input stream may be requested to arrive at the system in order of increasing timestamps. Alternatively, a relation (also referred to as a “time varying relation,” and not to be confused with “relational data,” which may include data from a relational database) may be a mapping from the time domain to an unbounded bag of tuples of the schema R. In some examples, a relation may be an unordered, time-varying bag of tuples (i.e., an instantaneous relation). In some cases, at each instance of time, a relation may be a bounded set. It can also be represented as a sequence of timestamped tuples that may include insertions, deletes, and/or updates to capture the changing state of the relation. Similar to streams, a relation may have a fixed schema to which each tuple of the relation may conform. Further, as used herein, a continuous query may generally be capable of processing data of (i.e., queried against) a stream and/or a relation. Additionally, the relation may reference data of the stream.

In some examples, business intelligence (BI) may help drive and optimize business operations at particular intervals (e.g., on a daily basis in some cases). This type of BI is usually called operational business intelligence, real-time business intelligence, or operational intelligence (OI). Operational Intelligence, in some examples, blurs the line between BI and business activity monitoring (BAM). For example, BI may be focused on periodic queries of historic data. As such, it may have a backward-looking focus. However, BI may also be placed into operational applications, and it may therefore expand from a mere strategic analytical tool into the front lines in business operations. As such, BI systems may also be configured to analyze event streams and compute aggregates in real time.

Additionally, in some examples, OI is a form of real-time dynamic, business analytics that can deliver visibility and insight into business operations. OI is often linked to or compared with BI or real-time BI, in the sense that both help make sense out of large amounts of information. But there are some basic differences: OI may be primarily activity-centric, whereas BI may be primarily data-centric. Additionally, OI may be more appropriate for detecting and responding to a developing situation (e.g., trend and pattern), unlike BI which may traditionally be used as an after-the-fact and report-based approach to identifying patterns.

In some examples, a business event analysis and monitoring (BEAM) system may include a CQL engine to process and/or receive in-flight data. For example, a CQL engine may be an in-memory real-time event processing engine configured to query or otherwise process incoming real-time information (e.g., BI or OI). The CQL engine may utilize or understand temporal semantics and be configured to allow definition of a window of data to process. Utilizing a CQL engine may, in some cases, involve always running a query on incoming data.

In some aspects, the CQL engine may include a full blown query language. As such, a user may specify computations in terms of a query. Additionally, the CQL engine may be designed for optimizing memory, utilizing query language features, operator sharing, rich pattern matching, rich language constructs, etc. Additionally, in some examples, the CQL engine may process both historical data and streaming data. For example, a user can set a query to send an alert when California sales hit above a certain target. Thus, in some examples, the alert may be based at least in part on historical sales data as well as incoming live (i.e., real-time) sales data.

In some examples, the CQL engine or other features of the below described concepts may be configured to combine a historical context (i.e., warehouse data) with incoming data in a real-time fashion. Thus, in some cases, the present disclosure may describe the boundary of database stored information and in-flight information. Both the database stored information and the inflight information may include BI data. As such, the database may, in some examples, be a BI server or it may be any type of database. Further, in some examples, the features of the present disclosure may enable the implementation of the above features without users knowing how to program or otherwise write code. In other words, the features may be provided in a feature-rich user interface (UI) or other manner that allows non-developers to implement the combination of historical data with real-time data.

The techniques described above and below may be implemented in a number of ways and in a number of contexts. Several example implementations and contexts are provided with reference to the following figures, as described below in more detail. However, the following implementations and contexts are but a few of many.

FIG. 1 depicts a simplified example system or architecture 100 in which techniques for guaranteeing event order may be implemented. In architecture 100, one or more users 102 (e.g., account holders) may utilize user computing devices 104(1)-(N) (collectively, “user devices 104”) to access one or more service provider computers 106 via one or more networks 108. In some aspects, the service provider computers 106 may also be in communication with one or more streaming data source computers 110 and/or one or more databases 112 via the networks 108. For example, the users 102 may utilize the service provider computers 106 to access or otherwise manage data of the streaming data source computers 110 and/or the databases 112 (e.g., queries may be run against either or both of 110, 112). The databases 112 may be relational databases, SQL servers, or the like and may, in some examples, manage historical data, event data, relations, archived relations, or the like on behalf of the users 102. Additionally, the databases 112 may receive or otherwise store data provided by the streaming data source computers 110. In some examples, the users 102 may utilize the user devices 104 to interact with the service provider computers 106 by providing queries (also referred to as “query statements”) or other requests for data (e.g., historical event data, streaming event data, etc.). Such queries or requests may then be executed by the service provider computers 106 to process data of the databases 112 and/or incoming data from the streaming data source computers 110. Further, in some examples, the streaming data source computers 110 and/or the databases 112 may be part of an integrated, distributed environment associated with the service provider computers 106.

In some examples, the networks 108 may include any one or a combination of multiple different types of networks, such as cable networks, the Internet, wireless networks, cellular networks, intranet systems, and/or other private and/or public networks. While the illustrated example represents the users 102 accessing the service provider computers 106 over the networks 108, the described techniques may equally apply in instances where the users 102 interact with one or more service provider computers 106 via the one or more user devices 104 over a landline phone, via a kiosk, or in any other manner. It is also noted that the described techniques may apply in other client/server arrangements (e.g., set-top boxes, etc.), as well as in non-client/server arrangements (e.g., locally stored applications, etc.).

The user devices 104 may be any type of computing device such as, but not limited to, a mobile phone, a smart phone, a personal digital assistant (PDA), a laptop computer, a desktop computer, a thin-client device, a tablet PC, etc. In some examples, the user devices 104 may be in communication with the service provider computers 106 via the networks 108, or via other network connections. Further, the user devices 104 may also be configured to provide one or more queries or query statements for requesting data of the databases 112 (or other data stores) to be processed.

In some aspects, the service provider computers 106 may also be any type of computing devices such as, but not limited to, mobile, desktop, thin-client, and/or cloud computing devices, such as servers. In some examples, the service provider computers 106 may be in communication with the user devices 104 via the networks 108, or via other network connections. The service provider computers 106 may include one or more servers, perhaps arranged in a cluster, as a server farm, or as individual servers not associated with one another. These servers may be configured to perform or otherwise host features described herein including, but not limited to, the management of archived relations, configurable data windows associated with archived relations, and/or accurately counting change events associated with managing archived relations described herein. Additionally, in some aspects, the service provider computers 106 may be configured as part of an integrated, distributed computing environment that includes the streaming data source computers 110 and/or the databases 112.

In one illustrative configuration, the service provider computers 106 may include at least one memory 136 and one or more processing units (or processor(s)) 138. The processor(s) 138 may be implemented as appropriate in hardware, computer-executable instructions, firmware, or combinations thereof. Computer-executable instruction or firmware implementations of the processor(s) 138 may include computer-executable or machine-executable instructions written in any suitable programming language to perform the various functions described.

The memory 136 may store program instructions that are loadable and executable on the processor(s) 138, as well as data generated during the execution of these programs. Depending on the configuration and type of service provider computers 106, the memory 136 may be volatile (such as random access memory (RAM)) and/or non-volatile (such as read-only memory (ROM), flash memory, etc.). The service provider computers 106 or servers may also include additional storage 140, which may include removable storage and/or non-removable storage. The additional storage 140 may include, but is not limited to, magnetic storage, optical disks, and/or tape storage. The disk drives and their associated computer-readable media may provide non-volatile storage of computer-readable instructions, data structures, program modules, and other data for the computing devices. In some implementations, the memory 136 may include multiple different types of memory, such as static random access memory (SRAM), dynamic random access memory (DRAM), or ROM.

The memory 136, the additional storage 140, both removable and non-removable, are all examples of computer-readable storage media. For example, computer-readable storage media may include volatile or non-volatile, removable or non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. The memory 136 and the additional storage 140 are all examples of computer storage media.

The service provider computers 106 may also contain communications connection(s) 142 that allow the identity interface computers 120 to communicate with a stored database, another computing device or server, user terminals, and/or other devices on the networks 108. The service provider computers 106 may also include input/output (I/O) device(s) 144, such as a keyboard, a mouse, a pen, a voice input device, a touch input device, a display, one or more speakers, a printer, etc.

Turning to the contents of the memory 136 in more detail, the memory 136 may include an operating system 146 and one or more application programs or services for implementing the features disclosed herein including at least a warm-up module 148, an out-of-order detection module 150 (e.g., utilizing the Leslie Lamport algorithm or the like), and/or skip-beat module 152. The warm-up module 148 may be configured to enable the warm-up period described above. The out-of-order detection module 150 may be configured to enable detection of out-of-order events, when events are received. And, the skip-beat module 152 may be configured to determine when events have been filtered out, and generate skip-beats as well as insert them into the streams when appropriate. As used herein, modules may refer to programming modules executed by servers or clusters of servers that are part of a service. In this particular context, the modules may be executed by the servers or clusters of servers that are part of the service provider computers 106.

FIG. 2 depicts a simplified high level diagram of an event processing system 200 that may incorporate an embodiment of the present disclosure. Event processing system 200 may comprise one or more event sources (204, 206, 208), an event processing server (EPS) 202 (also referred to as CQ Service 202) that is configured to provide an environment for processing event streams, and one or more event sinks (210, 212). The event sources generate event streams that are received by EPS 202. EPS 202 may receive one or more event streams from one or more event sources. For example, as shown in FIG. 2, EPS 202 receives an input event stream 214 from event source 204, a second input event stream 216 from event source 206, and a third event stream 218 from event source 208. One or more event processing applications (220, 222, and 224) may be deployed on and be executed by EPS 202. An event processing application executed by EPS 202 may be configured to listen to one or more input event streams, process the events received via the one or more event streams based upon processing logic that selects one or more events from the input event streams as notable events. The notable events may then be sent to one or more event sinks (210, 212) in the form of one or more output event streams. For example, in FIG. 2, EPS 202 outputs an output event stream 226 to event sink 210, and a second output event stream 228 to event sink 212. In certain embodiments, event sources, event processing applications, and event sinks are decoupled from each other such that one can add or remove any of these components without causing changes to the other components.

In one embodiment, EPS 202 may be implemented as a Java server comprising a lightweight Java application container, such as one based upon Equinox OSGi, with shared services. In some embodiments, EPS 202 may support ultra-high throughput and microsecond latency for processing events, for example, by using JRockit Real Time. EPS 202 may also provide a development platform (e.g., a complete real time end-to-end Java Event-Driven Architecture (EDA) development platform) including tools (e.g., Oracle CEP Visualizer and Oracle CEP IDE) for developing event processing applications.

An event processing application is configured to listen to one or more input event streams, execute logic (e.g., a query) for selecting one or more notable events from the one or more input event streams, and output the selected notable events to one or more event sources via one or more output event streams. FIG. 2 provides a drilldown for one such event processing application 220. As shown in FIG. 2, event processing application 220 is configured to listen to input event stream 218, execute a query 230 comprising logic for selecting one or more notable events from input event stream 218, and output the selected notable events via output event stream 228 to event sink 212. Examples of event sources include, without limitation, an adapter (e.g., JMS, HTTP, and file), a channel, a processor, a table, a cache, and the like. Examples of event sinks include, without limitation, an adapter (e.g., JMS, HTTP, and file), a channel, a processor, a cache, and the like.

Although event processing application 220 in FIG. 2 is shown as listening to one input stream and outputting selected events via one output stream, this is not intended to be limiting. In alternative embodiments, an event processing application may be configured to listen to multiple input streams received from one or more event sources, select events from the monitored streams, and output the selected events via one or more output event streams to one or more event sinks. The same query can be associated with more than one event sink and with different types of event sinks.

Due to its unbounded nature, the amount of data that is received via an event stream is generally very large. Consequently, it is generally impractical and undesirable to store or archive all the data for querying purposes. The processing of event streams requires processing of the events in real time as the events are received by EPS 202 without having to store all the received events data. Accordingly, EPS 202 provides a special querying mechanism that enables processing of events to be performed as the events are received by EPS 202 without having to store all the received events.

Event-driven applications are rule-driven and these rules may be expressed in the form of continuous queries that are used to process input streams. A continuous query may comprise instructions (e.g., business logic) that identify the processing to be performed for received events including what events are to be selected as notable events and output as results of the query processing. Continuous queries may be persisted to a data store and used for processing input streams of events and generating output streams of events. Continuous queries typically perform filtering and aggregation functions to discover and extract notable events from the input event streams. As a result, the number of outbound events in an output event stream is generally much lower than the number of events in the input event stream from which the events are selected.

Unlike a SQL query that is run once on a finite data set, a continuous query that has been registered by an application with EPS 202 for a particular event stream may be executed each time that an event is received in that event stream. As part of the continuous query execution, EPS 202 evaluates the received event based upon instructions specified by the continuous query to determine whether one or more events are to be selected as notable events, and output as a result of the continuous query execution.

The continuous query may be programmed using different languages. In certain embodiments, continuous queries may be configured using the CQL provided by Oracle Corporation and used by Oracle's Complex Events Processing (CEP) product offerings. Oracle's CQL is a declarative language that can be used to program queries (referred to as CQL queries) that can be executed against event streams. In certain embodiments, CQL is based upon SQL with added constructs that support processing of streaming events data.

In one embodiment, an event processing application may be composed of the following component types:

(1) One or more adapters that interface directly to the input and output stream and relation sources and sinks. Adapters are configured to understand the input and output stream protocol, and are responsible for converting the event data into a normalized form that can be queried by an application processor. Adapters may forward the normalized event data into channels or output streams and relation sinks. Event adapters may be defined for a variety of data sources and sinks.

(2) One or more channels that act as event processing endpoints. Among other things, channels are responsible for queuing event data until the event processing agent can act upon it.

(2) One or more application processors (or event processing agents) are configured to consume normalized event data from a channel, process it using queries to select notable events, and forward (or copy) the selected notable events to an output channel.

(4) One or more beans are configured to listen to the output channel, and are triggered by the insertion of a new event into the output channel. In some embodiments, this user code is a plain-old-Java-object (POJO). The user application can make use of a set of external services, such as JMS, Web services, and file writers, to forward the generated events to external event sinks.

(5) Event beans may be registered to listen to the output channel, and are triggered by the insertion of a new event into the output channel. In some embodiments, this user code may use the Oracle CEP event bean API so that the bean can be managed by Oracle CEP.

In one embodiment, an event adapter provides event data to an input channel. The input channel is connected to a CQL processor associated with one or more CQL queries that operate on the events offered by the input channel. The CQL processor is connected to an output channel to which query results are written.

In some embodiments, an assembly file may be provided for an event processing application describing the various components of the event processing application, how the components are connected together, event types processed by the application. Separate files may be provided for specifying the continuous query or business logic for selection of events.

It should be appreciated that system 200 depicted in FIG. 2 may have other components than those depicted in FIG. 2. Further, the embodiment shown in FIG. 2 is only one example of a system that may incorporate an embodiment of the present disclosure. In some other embodiments, system 200 may have more or fewer components than shown in FIG. 2, may combine two or more components, or may have a different configuration or arrangement of components. System 200 can be of various types including a personal computer, a portable device (e.g., a mobile telephone or device), a workstation, a network computer, a mainframe, a kiosk, a server, or any other data processing system. In some other embodiments, system 200 may be configured as a distributed system where one or more components of system 200 are distributed across one or more networks in the cloud.

The one or more of the components depicted in FIG. 2 may be implemented in software, in hardware, or combinations thereof. In some embodiments, the software may be stored in memory (e.g., a non-transitory computer-readable medium), on a memory device, or some other physical memory and may be executed by one or more processing units (e.g., one or more processors, one or more processor cores, one or more GPUs, etc.).

Illustrative methods and systems for implementing the hybrid execution of continuous and scheduled queries are described above. Some or all of these systems and methods may, but need not, be implemented at least partially by architectures and processes such as those shown at least in FIGS. 1-2 above.

FIGS. 3-5 are flowcharts of methods 300, 400, and 500, respectively, for guaranteeing the event order of multi-stage processing in accordance with an embodiment of the present disclosure. Implementations or processing of methods 300, 400, and 500 depicted in FIGS. 3-5 may be performed by software (e.g., instructions or code modules) when executed by a central processing unit (CPU or processor) of a logic machine, such as a computer system or information processing device, by hardware components of an electronic device or application-specific integrated circuits, or by combinations of software and hardware elements. Each of the steps of any of the processes described herein and below may be performed in any order, may be omitted (or otherwise skipped), may be replaced by other steps, and/or may be performed repeatedly or recursively, as desired.

Method 300 depicted in FIG. 3 may begin at 302 where a first event of an event stream may be determined (or identified) based at least in part on a warmup period that takes place at least until a timer expires. In some examples, at 304, an event counter may be initialized with a timestamp of the first event. Additional events of the event stream may be processed at 306. The additional events may have been batched before the timer expired. In some examples, filtered events may be identified at 308. The filtered events may have been filtered out by an upstream stage. At 310, a skip-beat may be generated and/or inserted into the stream for the filtered event. At 312, subsequent events of the event stream may be received. In some cases, out-of-order events may be identified at 314. The method 300 may, in some examples, end at 316 by processing subsequent events in order and/or guaranteeing that subsequent events will be processed in order. This may be done independent of whether each incoming event is an actual event or a skip-beat. In other words, even if a skip-beat is received, each event will be processed in order. In some examples, a skip-beat is not an actual event because it does not include event data (e.g., it is a dummy event that enables the CEP engine to continue processing the stream without waiting for the event that was filtered).

FIG. 4 is a flowchart of method 400 for guaranteeing the event order of multi-stage processing in accordance with an embodiment of the present disclosure. Method 400 depicted in FIG. 4 may begin at 402, where a timer may be started. In some examples, events of a stream may be received until the timer expires at 404. At 406, the incoming events may be re-sequenced (or sequenced) in chronological order (e.g., put in order if they were out of order). The warmup period of method 400 may end at 408, where a first event is identified as the first event based at least in part on that event having the highest (oldest) timestamp.

FIG. 5 is a flowchart of method 500 for guaranteeing the event order of multi-stage processing in accordance with an embodiment of the present disclosure. Method 500 depicted in FIG. 5 may begin at 502, where events are received, and it is determined what type of event was received and the timestamp of the event. In some examples, at 502, if the skip-beat or actual event arrives that has a timestamp higher than the next expected timestamp, the event is added to a buffer and a timer is started. The timer may have a pre-configured expiration interval. At 504, more actual events or skip-beats are received. If they have timestamps higher than the next expected timestamp, they are also added to the buffer and the timer continues to run. At 506, when an actual event or skip-beat arrives with a timestamp that is the same as the next expected timestamp, the timer can be turned off, and events in the buffer can be re-sequenced and/or processed. Note, that skip-beats will continue to be propagated when appropriate. At 508, when an actual event or skip-beat arrives with a timestamp lower than the next expected timestamp, the event can be discarded as out-of-band. In some examples, the method 500 may end at 510 by re-sequencing and/or processing buffered events when the timer expires. The method 500 may also continue to propagate skip-beats as desired during this time.

FIG. 6 depicts a simplified diagram of a distributed system 600 for implementing one of the embodiments. In the illustrated embodiment, distributed system 600 includes one or more client computing devices 602, 604, 606, and 608, which are configured to execute and operate a client application such as a web browser, proprietary client (e.g., Oracle Forms), or the like over one or more network(s) 610. Server 612 may be communicatively coupled with remote client computing devices 602, 604, 606, and 608 via network 610.

In various embodiments, server 612 may be adapted to run one or more services or software applications provided by one or more of the components of the system. The services or software applications can include nonvirtual and virtual environments. Virtual environments can include those used for virtual events, tradeshows, simulators, classrooms, shopping exchanges, and enterprises, whether two- or three-dimensional (3D) representations, page-based logical environments, or otherwise. In some embodiments, these services may be offered as web-based or cloud services or under a Software as a Service (SaaS) model to the users of client computing devices 602, 604, 606, and/or 608. Users operating client computing devices 602, 604, 606, and/or 608 may in turn utilize one or more client applications to interact with server 612 to utilize the services provided by these components.

In the configuration depicted in the figure, the software components 618, 620 and 622 of system 600 are shown as being implemented on server 612. In other embodiments, one or more of the components of system 600 and/or the services provided by these components may also be implemented by one or more of the client computing devices 602, 604, 606, and/or 608. Users operating the client computing devices may then utilize one or more client applications to use the services provided by these components. These components may be implemented in hardware, firmware, software, or combinations thereof. It should be appreciated that various different system configurations are possible, which may be different from distributed system 600. The embodiment shown in the figure is thus one example of a distributed system for implementing an embodiment system and is not intended to be limiting.

Client computing devices 602, 604, 606, and/or 608 may be portable handheld devices (e.g., an iPhone®, cellular telephone, an iPad®, computing tablet, a personal digital assistant (PDA)) or wearable devices (e.g., a Google Glass® head mounted display), running software such as Microsoft Windows Mobile®, and/or a variety of mobile operating systems such as iOS, Windows Phone, Android, BlackBerry 8, Palm OS, and the like, and being Internet, e-mail, short message service (SMS), Blackberry®, or other communication protocol enabled. The client computing devices can be general purpose personal computers including, by way of example, personal computers and/or laptop computers running various versions of Microsoft Windows®, Apple Macintosh®, and/or Linux operating systems. The client computing devices can be workstation computers running any of a variety of commercially-available UNIX® or UNIX-like operating systems, including without limitation the variety of GNU/Linux operating systems, such as for example, Google Chrome OS. Alternatively, or in addition, client computing devices 602, 604, 606, and 608 may be any other electronic device, such as a thin-client computer, an Internet-enabled gaming system (e.g., a Microsoft Xbox gaming console with or without a Kinect® gesture input device), and/or a personal messaging device, capable of communicating over network(s) 610.

Although exemplary distributed system 600 is shown with four client computing devices, any number of client computing devices may be supported. Other devices, such as devices with sensors, etc., may interact with server 612.

Network(s) 610 in distributed system 600 may be any type of network familiar to those skilled in the art that can support data communications using any of a variety of commercially-available protocols, including without limitation TCP/IP (transmission control protocol/Internet protocol), SNA (systems network architecture), IPX (Internet packet exchange), AppleTalk, and the like. Merely by way of example, network(s) 610 can be a local area network (LAN), such as one based on Ethernet, Token-Ring and/or the like. Network(s) 610 can be a wide-area network and the Internet. It can include a virtual network, including without limitation a virtual private network (VPN), an intranet, an extranet, a public switched telephone network (PSTN), an infra-red network, a wireless network (e.g., a network operating under any of the Institute of Electrical and Electronics (IEEE) 602.11 suite of protocols, Bluetooth®, and/or any other wireless protocol); and/or any combination of these and/or other networks.

Server 612 may be composed of one or more general purpose computers, specialized server computers (including, by way of example, PC (personal computer) servers, UNIX® servers, mid-range servers, mainframe computers, rack-mounted servers, etc.), server farms, server clusters, or any other appropriate arrangement and/or combination. Server 612 can include one or more virtual machines running virtual operating systems, or other computing architectures involving virtualization. One or more flexible pools of logical storage devices can be virtualized to maintain virtual storage devices for the server. Virtual networks can be controlled by server 612 using software defined networking. In various embodiments, server 612 may be adapted to run one or more services or software applications described in the foregoing disclosure. For example, server 612 may correspond to a server for performing processing described above according to an embodiment of the present disclosure.

Server 612 may run an operating system including any of those discussed above, as well as any commercially available server operating system. Server 612 may also run any of a variety of additional server applications and/or mid-tier applications, including HTTP (hypertext transport protocol) servers, FTP (file transfer protocol) servers, CGI (common gateway interface) servers, JAVA® servers, database servers, and the like. Exemplary database servers include without limitation those commercially available from Oracle, Microsoft, Sybase, IBM (International Business Machines), and the like.

In some implementations, server 612 may include one or more applications to analyze and consolidate data feeds and/or event updates received from users of client computing devices 602, 604, 606, and 608. As an example, data feeds and/or event updates may include, but are not limited to, Twitter® feeds, Facebook® updates or real-time updates received from one or more third party information sources and continuous data streams, which may include real-time events related to sensor data applications, financial tickers, network performance measuring tools (e.g., network monitoring and traffic management applications), clickstream analysis tools, automobile traffic monitoring, and the like. Server 612 may also include one or more applications to display the data feeds and/or real-time events via one or more display devices of client computing devices 602, 604, 606, and 608.

Distributed system 600 may also include one or more databases 614 and 616. Databases 614 and 616 may reside in a variety of locations. By way of example, one or more of databases 614 and 616 may reside on a non-transitory storage medium local to (and/or resident in) server 612. Alternatively, databases 614 and 616 may be remote from server 612 and in communication with server 612 via a network-based or dedicated connection. In one set of embodiments, databases 614 and 616 may reside in a storage-area network (SAN). Similarly, any necessary files for performing the functions attributed to server 612 may be stored locally on server 612 and/or remotely, as appropriate. In one set of embodiments, databases 614 and 616 may include relational databases, such as databases provided by Oracle, that are adapted to store, update, and retrieve data in response to SQL-formatted commands.

FIG. 7 is a simplified block diagram of one or more components of a system environment 700 by which services provided by one or more components of an embodiment system may be offered as cloud services, in accordance with an embodiment of the present disclosure. In the illustrated embodiment, system environment 700 includes one or more client computing devices 704, 706, and 708 that may be used by users to interact with a cloud infrastructure system 702 that provides cloud services. The client computing devices may be configured to operate a client application such as a web browser, a proprietary client application (e.g., Oracle Forms), or some other application, which may be used by a user of the client computing device to interact with cloud infrastructure system 702 to use services provided by cloud infrastructure system 702.

It should be appreciated that cloud infrastructure system 702 depicted in the figure may have other components than those depicted. Further, the embodiment shown in the figure is only one example of a cloud infrastructure system that may incorporate an embodiment of the disclosure. In some other embodiments, cloud infrastructure system 702 may have more or fewer components than shown in the figure, may combine two or more components, or may have a different configuration or arrangement of components.

Client computing devices 704, 706, and 708 may be devices similar to those described above for 602, 604, 606, and 608.

Although exemplary system environment 700 is shown with three client computing devices, any number of client computing devices may be supported. Other devices such as devices with sensors, etc. may interact with cloud infrastructure system 702.

Network(s) 710 may facilitate communications and exchange of data between clients 704, 706, and 708 and cloud infrastructure system 702. Each network may be any type of network familiar to those skilled in the art that can support data communications using any of a variety of commercially-available protocols, including those described above for network(s) 610.

Cloud infrastructure system 702 may comprise one or more computers and/or servers that may include those described above for server 612.

In certain embodiments, services provided by the cloud infrastructure system may include a host of services that are made available to users of the cloud infrastructure system on demand, such as online data storage and backup solutions, Web-based e-mail services, hosted office suites and document collaboration services, database processing, managed technical support services, and the like. Services provided by the cloud infrastructure system can dynamically scale to meet the needs of its users. A specific instantiation of a service provided by cloud infrastructure system is referred to herein as a “service instance.” In general, any service made available to a user via a communication network, such as the Internet, from a cloud service provider's system is referred to as a “cloud service.” Typically, in a public cloud environment, servers and systems that make up the cloud service provider's system are different from the customer's own on-premises servers and systems. For example, a cloud service provider's system may host an application, and a user may, via a communication network such as the Internet, on demand, order and use the application.

In some examples, a service in a computer network cloud infrastructure may include protected computer network access to storage, a hosted database, a hosted web server, a software application, or other service provided by a cloud vendor to a user, or as otherwise known in the art. For example, a service can include password-protected access to remote storage on the cloud through the Internet. As another example, a service can include a web service-based hosted relational database and a script-language middleware engine for private use by a networked developer. As another example, a service can include access to an email software application hosted on a cloud vendor's web site.

In certain embodiments, cloud infrastructure system 702 may include a suite of applications, middleware, and database service offerings that are delivered to a customer in a self-service, subscription-based, elastically scalable, reliable, highly available, and secure manner. An example of such a cloud infrastructure system is the Oracle Public Cloud provided by the present assignee.

‘Big data’ can be hosted and/or manipulated by the infrastructure system on many levels and at different scales. Extremely large data sets can be stored and manipulated by analysts and researchers to visualize large amounts of data, detect trends, and/or otherwise interact with the data. Tens, hundreds, or thousands of processors linked in parallel can act upon such data in order to present it or simulate external forces on the data or what it represents. These data sets can involve structured data, such as that organized in a database or otherwise according to a structured model, and/or unstructured data (e.g., emails, images, data blobs (binary large objects), web pages, complex event processing). By leveraging an ability of an embodiment to relatively quickly focus more (or fewer) computing resources upon an objective, the cloud infrastructure system may be better available to carry out tasks on large data sets based on demand from a business, government agency, research organization, private individual, group of like-minded individuals or organizations, or other entity.

In various embodiments, cloud infrastructure system 702 may be adapted to automatically provision, manage and track a customer's subscription to services offered by cloud infrastructure system 702. Cloud infrastructure system 702 may provide the cloud services via different deployment models. For example, services may be provided under a public cloud model in which cloud infrastructure system 702 is owned by an organization selling cloud services (e.g., owned by Oracle) and the services are made available to the general public or different industry enterprises. As another example, services may be provided under a private cloud model in which cloud infrastructure system 702 is operated solely for a single organization and may provide services for one or more entities within the organization. The cloud services may also be provided under a community cloud model in which cloud infrastructure system 702 and the services provided by cloud infrastructure system 702 are shared by several organizations in a related community. The cloud services may also be provided under a hybrid cloud model, which is a combination of two or more different models.

In some embodiments, the services provided by cloud infrastructure system 702 may include one or more services provided under Software as a Service (SaaS) category, Platform as a Service (PaaS) category, Infrastructure as a Service (IaaS) category, or other categories of services including hybrid services. A customer, via a subscription order, may order one or more services provided by cloud infrastructure system 702. Cloud infrastructure system 702 then performs processing to provide the services in the customer's subscription order.

In some embodiments, the services provided by cloud infrastructure system 702 may include, without limitation, application services, platform services and infrastructure services. In some examples, application services may be provided by the cloud infrastructure system via a SaaS platform. The SaaS platform may be configured to provide cloud services that fall under the SaaS category. For example, the SaaS platform may provide capabilities to build and deliver a suite of on-demand applications on an integrated development and deployment platform. The SaaS platform may manage and control the underlying software and infrastructure for providing the SaaS services. By utilizing the services provided by the SaaS platform, customers can utilize applications executing on the cloud infrastructure system. Customers can acquire the application services without the need for customers to purchase separate licenses and support. Various different SaaS services may be provided. Examples include, without limitation, services that provide solutions for sales performance management, enterprise integration, and business flexibility for large organizations.

In some embodiments, platform services may be provided by the cloud infrastructure system via a PaaS platform. The PaaS platform may be configured to provide cloud services that fall under the PaaS category. Examples of platform services may include without limitation services that enable organizations (such as Oracle) to consolidate existing applications on a shared, common architecture, as well as the ability to build new applications that leverage the shared services provided by the platform. The PaaS platform may manage and control the underlying software and infrastructure for providing the PaaS services. Customers can acquire the PaaS services provided by the cloud infrastructure system without the need for customers to purchase separate licenses and support. Examples of platform services include, without limitation, Oracle Java Cloud Service (JCS), Oracle Database Cloud Service (DBCS), and others.

By utilizing the services provided by the PaaS platform, customers can employ programming languages and tools supported by the cloud infrastructure system and also control the deployed services. In some embodiments, platform services provided by the cloud infrastructure system may include database cloud services, middleware cloud services (e.g., Oracle Fusion Middleware services), and Java cloud services. In one embodiment, database cloud services may support shared service deployment models that enable organizations to pool database resources and offer customers a Database as a Service in the form of a database cloud. Middleware cloud services may provide a platform for customers to develop and deploy various business applications, and Java cloud services may provide a platform for customers to deploy Java applications, in the cloud infrastructure system.

Various different infrastructure services may be provided by an IaaS platform in the cloud infrastructure system. The infrastructure services facilitate the management and control of the underlying computing resources, such as storage, networks, and other fundamental computing resources for customers utilizing services provided by the SaaS platform and the PaaS platform.

In certain embodiments, cloud infrastructure system 702 may also include infrastructure resources 730 for providing the resources used to provide various services to customers of the cloud infrastructure system. In one embodiment, infrastructure resources 730 may include pre-integrated and optimized combinations of hardware, such as servers, storage, and networking resources to execute the services provided by the PaaS platform and the SaaS platform.

In some embodiments, resources in cloud infrastructure system 702 may be shared by multiple users and dynamically re-allocated per demand. Additionally, resources may be allocated to users in different time zones. For example, cloud infrastructure system 730 may enable a first set of users in a first time zone to utilize resources of the cloud infrastructure system for a specified number of hours and then enable the re-allocation of the same resources to another set of users located in a different time zone, thereby maximizing the utilization of resources.

In certain embodiments, a number of internal shared services 732 may be provided that are shared by different components or modules of cloud infrastructure system 702 and by the services provided by cloud infrastructure system 702. These internal shared services may include, without limitation, a security and identity service, an integration service, an enterprise repository service, an enterprise manager service, a virus scanning and white list service, a high availability, backup and recovery service, service for enabling cloud support, an email service, a notification service, a file transfer service, and the like.

In certain embodiments, cloud infrastructure system 702 may provide comprehensive management of cloud services (e.g., SaaS, PaaS, and IaaS services) in the cloud infrastructure system. In one embodiment, cloud management functionality may include capabilities for provisioning, managing and tracking a customer's subscription received by cloud infrastructure system 702, and the like.

In one embodiment, as depicted in the figure, cloud management functionality may be provided by one or more modules, such as an order management module 720, an order orchestration module 722, an order provisioning module 724, an order management and monitoring module 726, and an identity management module 728. These modules may include or be provided using one or more computers and/or servers, which may be general purpose computers, specialized server computers, server farms, server clusters, or any other appropriate arrangement and/or combination.

In exemplary operation 734, a customer using a client device, such as client device 704, 706 or 708, may interact with cloud infrastructure system 702 by requesting one or more services provided by cloud infrastructure system 702 and placing an order for a subscription for one or more services offered by cloud infrastructure system 702. In certain embodiments, the customer may access a cloud User Interface (UI), cloud UI 712, cloud UI 714 and/or cloud UI 716 and place a subscription order via these UIs. The order information received by cloud infrastructure system 702 in response to the customer placing an order may include information identifying the customer and one or more services offered by the cloud infrastructure system 702 that the customer intends to subscribe to.

After an order has been placed by the customer, the order information is received via the cloud UIs, 712, 714 and/or 716.

At operation 736, the order is stored in order database 718. Order database 718 can be one of several databases operated by cloud infrastructure system 718 and operated in conjunction with other system elements.

At operation 738, the order information is forwarded to an order management module 720. In some instances, order management module 720 may be configured to perform billing and accounting functions related to the order, such as verifying the order, and upon verification, booking the order.

At operation 740, information regarding the order is communicated to an order orchestration module 722. Order orchestration module 722 may utilize the order information to orchestrate the provisioning of services and resources for the order placed by the customer. In some instances, order orchestration module 722 may orchestrate the provisioning of resources to support the subscribed services using the services of order provisioning module 724.

In certain embodiments, order orchestration module 722 enables the management of business processes associated with each order and applies business logic to determine whether an order should proceed to provisioning. At operation 742, upon receiving an order for a new subscription, order orchestration module 722 sends a request to order provisioning module 724 to allocate resources and configure those resources needed to fulfill the subscription order. Order provisioning module 724 enables the allocation of resources for the services ordered by the customer. Order provisioning module 724 provides a level of abstraction between the cloud services provided by cloud infrastructure system 700 and the physical implementation layer that is used to provision the resources for providing the requested services. Order orchestration module 722 may thus be isolated from implementation details, such as whether or not services and resources are actually provisioned on the fly or pre-provisioned and only allocated/assigned upon request.

At operation 744, once the services and resources are provisioned, a notification of the provided service may be sent to customers on client devices 704, 706 and/or 708 by order provisioning module 724 of cloud infrastructure system 702.

At operation 746, the customer's subscription order may be managed and tracked by an order management and monitoring module 726. In some instances, order management and monitoring module 726 may be configured to collect usage statistics for the services in the subscription order, such as the amount of storage used, the amount data transferred, the number of users, and the amount of system up time and system down time.

In certain embodiments, cloud infrastructure system 700 may include an identity management module 728. Identity management module 728 may be configured to provide identity services, such as access management and authorization services in cloud infrastructure system 700. In some embodiments, identity management module 728 may control information about customers who wish to utilize the services provided by cloud infrastructure system 702. Such information can include information that authenticates the identities of such customers and information that describes which actions those customers are authorized to perform relative to various system resources (e.g., files, directories, applications, communication ports, memory segments, etc.) Identity management module 728 may also include the management of descriptive information about each customer and about how and by whom that descriptive information can be accessed and modified.

FIG. 8 illustrates an exemplary computer system 800, in which various embodiments of the present disclosure may be implemented. The system 800 may be used to implement any of the computer systems described above. As shown in the figure, computer system 800 includes a processing unit 804 that communicates with a number of peripheral subsystems via a bus subsystem 802. These peripheral subsystems may include a processing acceleration unit 806, an I/O subsystem 808, a storage subsystem 818 and a communications subsystem 824. Storage subsystem 818 includes tangible computer-readable storage media 822 and a system memory 810.

Bus subsystem 802 provides a mechanism for letting the various components and subsystems of computer system 800 communicate with each other as intended. Although bus subsystem 802 is shown schematically as a single bus, alternative embodiments of the bus subsystem may utilize multiple buses. Bus subsystem 802 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. For example, such architectures may include an Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus, which can be implemented as a Mezzanine bus manufactured to the IEEE P1386.1 standard.

Processing unit 804, which can be implemented as one or more integrated circuits (e.g., a conventional microprocessor or microcontroller), controls the operation of computer system 800. One or more processors may be included in processing unit 804. These processors may include single core or multicore processors. In certain embodiments, processing unit 804 may be implemented as one or more independent processing units 832 and/or 834 with single or multicore processors included in each processing unit. In other embodiments, processing unit 804 may also be implemented as a quad-core processing unit formed by integrating two dual-core processors into a single chip.

In various embodiments, processing unit 804 can execute a variety of programs in response to program code and can maintain multiple concurrently executing programs or processes. At any given time, some or all of the program code to be executed can be resident in processor(s) 804 and/or in storage subsystem 818. Through suitable programming, processor(s) 804 can provide various functionalities described above. Computer system 800 may additionally include a processing acceleration unit 806, which can include a digital signal processor (DSP), a special-purpose processor, and/or the like.

I/O subsystem 808 may include user interface input devices and user interface output devices. User interface input devices may include a keyboard, pointing devices such as a mouse or trackball, a touchpad or touch screen incorporated into a display, a scroll wheel, a click wheel, a dial, a button, a switch, a keypad, audio input devices with voice command recognition systems, microphones, and other types of input devices. User interface input devices may include, for example, motion sensing and/or gesture recognition devices such as the Microsoft Kinect® motion sensor that enables users to control and interact with an input device, such as the Microsoft Xbox® 360 game controller, through a natural user interface using gestures and spoken commands. User interface input devices may also include eye gesture recognition devices such as the Google Glass® blink detector that detects eye activity (e.g., ‘blinking’ while taking pictures and/or making a menu selection) from users and transforms the eye gestures as input into an input device (e.g., Google Glass®). Additionally, user interface input devices may include voice recognition sensing devices that enable users to interact with voice recognition systems (e.g., Siri® navigator), through voice commands.

User interface input devices may also include, without limitation, three dimensional (3D) mice, joysticks or pointing sticks, gamepads and graphic tablets, and audio/visual devices such as speakers, digital cameras, digital camcorders, portable media players, webcams, image scanners, fingerprint scanners, barcode reader 3D scanners, 3D printers, laser rangefinders, and eye gaze tracking devices. Additionally, user interface input devices may include, for example, medical imaging input devices such as computed tomography, magnetic resonance imaging, position emission tomography, medical ultrasonography devices. User interface input devices may also include, for example, audio input devices such as MIDI keyboards, digital musical instruments and the like.

User interface output devices may include a display subsystem, indicator lights, or non-visual displays such as audio output devices, etc. The display subsystem may be a cathode ray tube (CRT), a flat-panel device, such as that using a liquid crystal display (LCD) or plasma display, a projection device, a touch screen, and the like. In general, use of the term “output device” is intended to include all possible types of devices and mechanisms for outputting information from computer system 800 to a user or other computer. For example, user interface output devices may include, without limitation, a variety of display devices that visually convey text, graphics and audio/video information such as monitors, printers, speakers, headphones, automotive navigation systems, plotters, voice output devices, and modems.

Computer system 800 may comprise a storage subsystem 818 that comprises software elements, shown as being currently located within a system memory 810. System memory 810 may store program instructions that are loadable and executable on processing unit 804, as well as data generated during the execution of these programs.

Depending on the configuration and type of computer system 800, system memory 810 may be volatile (such as random access memory (RAM)) and/or non-volatile (such as read-only memory (ROM), flash memory, etc.) The RAM typically contains data and/or program modules that are immediately accessible to and/or presently being operated and executed by processing unit 804. In some implementations, system memory 810 may include multiple different types of memory, such as static random access memory (SRAM) or dynamic random access memory (DRAM). In some implementations, a basic input/output system (BIOS), containing the basic routines that help to transfer information between elements within computer system 800, such as during start-up, may typically be stored in the ROM. By way of example, and not limitation, system memory 810 also illustrates application programs 812, which may include client applications, Web browsers, mid-tier applications, relational database management systems (RDBMS), etc., program data 814, and an operating system 816. By way of example, operating system 816 may include various versions of Microsoft Windows®, Apple Macintosh®, and/or Linux operating systems, a variety of commercially-available UNIX® or UNIX-like operating systems (including without limitation the variety of GNU/Linux operating systems, the Google Chrome® OS, and the like) and/or mobile operating systems such as iOS, Windows® Phone, Android® OS, BlackBerry® 8 OS, and Palm® OS operating systems.

Storage subsystem 818 may also provide a tangible computer-readable storage medium for storing the basic programming and data constructs that provide the functionality of some embodiments. Software (programs, code modules, instructions) that when executed by a processor provide the functionality described above may be stored in storage subsystem 818. These software modules or instructions may be executed by processing unit 804. Storage subsystem 818 may also provide a repository for storing data used in accordance with the present disclosure.

Storage subsystem 800 may also include a computer-readable storage media reader 820 that can further be connected to computer-readable storage media 822. Together and, optionally, in combination with system memory 810, computer-readable storage media 822 may comprehensively represent remote, local, fixed, and/or removable storage devices plus storage media for temporarily and/or more permanently containing, storing, transmitting, and retrieving computer-readable information.

Computer-readable storage media 822 containing code, or portions of code, can also include any appropriate media known or used in the art, including storage media and communication media, such as but not limited to, volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage and/or transmission of information. This can include tangible, non-transitory computer-readable storage media such as RAM, ROM, electronically erasable programmable ROM (EEPROM), flash memory or other memory technology, CD-ROM, digital versatile disk (DVD), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or other tangible computer readable media. When specified, this can also include nontangible, transitory computer-readable media, such as data signals, data transmissions, or any other medium which can be used to transmit the desired information and which can be accessed by computing system 800.

By way of example, computer-readable storage media 822 may include a hard disk drive that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive that reads from or writes to a removable, nonvolatile magnetic disk, and an optical disk drive that reads from or writes to a removable, nonvolatile optical disk such as a CD ROM, DVD, and Blu-Ray® disk, or other optical media. Computer-readable storage media 822 may include, but is not limited to, Zip® drives, flash memory cards, universal serial bus (USB) flash drives, secure digital (SD) cards, DVD disks, digital video tape, and the like. Computer-readable storage media 822 may also include, solid-state drives (SSD) based on non-volatile memory such as flash-memory based SSDs, enterprise flash drives, solid state ROM, and the like, SSDs based on volatile memory such as solid state RAM, dynamic RAM, static RAM, DRAM-based SSDs, magnetoresistive RAM (MRAM) SSDs, and hybrid SSDs that use a combination of DRAM and flash memory based SSDs. The disk drives and their associated computer-readable media may provide non-volatile storage of computer-readable instructions, data structures, program modules, and other data for computer system 800.

Communications subsystem 824 provides an interface to other computer systems and networks. Communications subsystem 824 serves as an interface for receiving data from and transmitting data to other systems from computer system 800. For example, communications subsystem 824 may enable computer system 800 to connect to one or more devices via the Internet. In some embodiments communications subsystem 824 can include radio frequency (RF) transceiver components for accessing wireless voice and/or data networks (e.g., using cellular telephone technology, advanced data network technology, such as 3G, 4G or EDGE (enhanced data rates for global evolution), WiFi (IEEE 602.11 family standards, or other mobile communication technologies, or any combination thereof), global positioning system (GPS) receiver components, and/or other components. In some embodiments communications subsystem 824 can provide wired network connectivity (e.g., Ethernet) in addition to or instead of a wireless interface.

In some embodiments, communications subsystem 824 may also receive input communication in the form of structured and/or unstructured data feeds 826, event streams 828, event updates 830, and the like on behalf of one or more users who may use computer system 800.

By way of example, communications subsystem 824 may be configured to receive data feeds 826 in real-time from users of social media networks and/or other communication services such as Twitter® feeds, Facebook® updates, web feeds such as Rich Site Summary (RSS) feeds, and/or real-time updates from one or more third party information sources.

Additionally, communications subsystem 824 may also be configured to receive data in the form of continuous data streams, which may include event streams 828 of real-time events and/or event updates 830, that may be continuous or unbounded in nature with no explicit end. Examples of applications that generate continuous data may include, for example, sensor data applications, financial tickers, network performance measuring tools (e.g. network monitoring and traffic management applications), clickstream analysis tools, automobile traffic monitoring, and the like.

Communications subsystem 824 may also be configured to output the structured and/or unstructured data feeds 826, event streams 828, event updates 830, and the like to one or more databases that may be in communication with one or more streaming data source computers coupled to computer system 800.

Computer system 800 can be one of various types, including a handheld portable device (e.g., an iPhone® cellular phone, an iPad® computing tablet, a PDA), a wearable device (e.g., a Google Glass® head mounted display), a PC, a workstation, a mainframe, a kiosk, a server rack, or any other data processing system.

Due to the ever-changing nature of computers and networks, the description of computer system 800 depicted in the figure is intended only as a specific example. Many other configurations having more or fewer components than the system depicted in the figure are possible. For example, customized hardware might also be used and/or particular elements might be implemented in hardware, firmware, software (including applets), or a combination. Further, connection to other computing devices, such as network input/output devices, may be employed. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will appreciate other ways and/or methods to implement the various embodiments.

In the foregoing specification, aspects of the disclosure are described with reference to specific embodiments thereof, but those skilled in the art will recognize that the disclosure is not limited thereto. Various features and aspects of the above-described disclosure may be used individually or jointly. Further, embodiments can be utilized in any number of environments and applications beyond those described herein without departing from the broader spirit and scope of the specification. The specification and drawings are, accordingly, to be regarded as illustrative rather than restrictive. 

What is claimed is:
 1. A method, comprising: determining a first event of a sequence of events that are received as part of an event stream; initializing a value of an event counter with a timestamp of the first event; processing additional events of the event stream; identifying a filtered event of the event stream; generating a skip-beat for the filtered event; inserting the skip-beat into the event stream; receiving subsequent events of the event stream; identifying an out-of-order event of the event stream; and processing subsequent events in order of the timestamp associated with each of the subsequent events independent of whether a next event in the event stream is an actual event or a skip-beat.
 2. The method of claim 1, wherein the first event is determined by: starting a timer; receiving a set of events of the sequence of events until the timer expires; re-sequencing the set of events in chronological order; and identifying the first event as an event of the re-sequenced set with a highest timestamp.
 3. The method of claim 2, wherein the additional events were batched before the timer expired.
 4. The method of claim 1, wherein the filtered event was filtered out by an upstream stage.
 5. The method of claim 1, wherein the actual event comprises event data corresponding to the event stream.
 6. A computer-readable medium storing program code that when executed by a processor of a computing system causes the processor to perform operations comprising: determining a first event of a sequence of events; initializing a value of an event counter with a timestamp of the first event; processing additional events; identifying a filtered event; generating a skip-beat for the filtered event; receiving subsequent events; identifying an out-of-order event; and processing subsequent events in order of the timestamp associated with each of the subsequent events independent of whether a next event in the event stream is an actual event or a skip-beat.
 7. The computer-readable medium of claim 6, wherein the first event is determined by: starting a timer; receiving a set of events of the sequence of events until the timer expires; re-sequencing the set of events in chronological order; and identifying the first event as an event of the re-sequenced set with a highest timestamp.
 8. The computer-readable medium of claim 7, wherein the additional events were batched before the timer expired.
 9. The computer-readable medium of claim 6, wherein the filtered event was filtered out by an upstream stage.
 10. The computer-readable medium of claim 6, wherein the first event is received as part of an event stream.
 11. The computer-readable medium of claim 10, wherein at least one of the additional events or the filtered event are received as part of the event stream.
 12. The computer-readable medium of claim 10, wherein the operations further comprise inserting the skip-beat into the event stream.
 13. The computer-readable medium of claim 6, wherein the out-of-order event is discarded.
 14. A system, comprising: a memory configured to store computer-executable instructions; and a processor configured to access the memory and execute the computer-executable instructions to at least: determine a first event of a sequence of events; initialize a value of an event counter with a timestamp of the first event; process additional events; identify a filtered event; generate a skip-beat for the filtered event; receive subsequent events; identify an out-of-order event; and process subsequent events in order of the timestamp associated with each of the subsequent events independent of whether a next event in the event stream is an actual event or a skip-beat.
 15. The system of claim 14, wherein the processor further executes the computer-executable instructions to at least: start a timer; receive a set of events of the sequence of events until the timer expires; re-sequence the set of events in chronological order; and identify the first event as an event of the re-sequenced set with a highest timestamp.
 16. The system of claim 15, wherein the additional events were batched before the timer expired.
 17. The system of claim 14, wherein the filtered event was filtered out by an upstream stage.
 18. The system of claim 14, wherein the first event is received as part of an event stream.
 19. The system of claim 18, wherein at least one of the additional events or the filtered event are received as part of the event stream.
 20. The system of claim 18, wherein the operations further comprise inserting the skip-beat into the event stream. 